Dounreay waste plant application

22 January 2007

The UK Atomic Energy Authority (UKAEA) has lodged a planning application to construct an integrated plant to treat and store intermediate-level radioactive waste at Dounreay.

The waste to be handled by the facility includes the raffinates from the recycling of used nuclear fuel from the site's two fast reactors. About 200 cubic meters of raffinatesbuilt up during recycling operations, which separated reusableplutonium and neptunium from waste products. The liquid raffinates, which UKAEA said account for 50% of radioactive inventory and 80% of the radioactive hazard at Dounreay, are currently stored in underground tanks that are set to be cleaned out for decommissioning.

Inside the new £120 million ($237 million) plant, the raffinates would be solidified by blending with a mix of "cementitious powders" and set inside 500 l stainless steel drums. The wastes would then be stored until a UK national radioactive waste repository becomes available. This method was identified as the best practicable environmental option by a UKAEA study, in favour of vitrification (drying liquid waste and mixing the resultant powder with glass). Norman Harrison, UKAEA's director at Dounreay said: "Cementation is a tried and trusted technology for conditioning intermediate-level waste. Innovation in our thinking means we can now reduce the single largest hazard at Dounreay on an earlier timescale and at substantially lower cost to the taxpayer."

The plant will also immobilise other liquid wastes and encapsulate solid waste from historic operations. Construction of the plant could begin in 2007 and it could treat its first waste in 2012, subject to consent from regulators, the Nuclear Installations Inspectorate.

The Dounreay Fast Reactor (DFR) operated from 1962 to 1977, while its successor the Prototype Fast Reactor (PFR) operated from 1975 to 1994. Although the units delivered 13 MWe and 254 MWe to the UK grid respectively, their technology was not considered successful enough to pursue for a fleet of such units.